1 Temporal sensitivity and Motion If the system is linear how do we use linear systems theory? Temporal ﬂicker sensitivity Temporal ﬂicker sensitivity Sensitivity to ﬂickering light (Wilkens) Early ﬁlm 24 frames/second - due to limits on the speed of ﬁlm ﬁlm ﬂickered Episcotister - shows each frame 3 times 72 frames/sec But motion is still at 24 frames/sec Persistence Turn a spot on then off How much light do you need to see it? How brieﬂy can it be on?

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Persistence Turn a spot on then off How much light do you need to see it? How brieﬂy can it be on? Time Intensity Persistence Turn a spot on then off How much light do you need to see it? How brieﬂy can it be on? Time What matters is the total amount of light Time x intensity > Threshold Persistence Turn a spot on then off How much light do you need to see it? How brieﬂy can it be on? Time What matters is the total amount of light Time x intensity > Threshold Persistence Turn a spot on then off How much light do you need to see it? How brieﬂy can it be on? Time What matters is the total amount of light Time x intensity > Threshold As long as time < 100 msecs Persistence But 100 msecs is a long time Relatively slow movement should appear blurred (e.g., like night cameras) Persistence Receptive ﬁelds integrate in the direction of motion than 100 msecs. Past 100 msecs moving dots appear sharper. Propose that this involves motion selective neurons integrating across time and space Takes 100 msecs to engage.

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